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Stimulated Raman scattering (SRS) has attracted significant attention recently for providing high-sensitivity and background-free chemical characterization without exogenous labeling. For the laser system of SRS, the current benchmark is the combination of a pico- or femtosecond mode-locked solid-state oscillator and a synchronously pumped optical parametric oscillator (OPO), offering two central wavelengths λpump and λStokes to match the desired Raman modes. Despite great success, the phase-sensitive nature of degenerate OPO hampers its access to low-frequency Raman shifts, and the inability to independently adjust the second wavelength prevents the OPO source from electronic pre- resonance (EPR) detection for desirable molecules.
In this work, we demonstrated an SRS spectro-microscopy system driven by a multiple-plate continuum (MPC) supercontinuum laser source, whose spectrum spans from 600 nm to 1300 nm, offering capabilities of dual-wavelength tunability across the entire Raman active region (0 to 4000 cm-1). We demonstrated SRS microspectroscopy across the fingerprint, silent, and C-H stretch Raman regions in acetonitrile solution. This novel light source allows significant contrast enhancement through EPR-SRS by tuning the pump wavelengths toward the absorption peak of dye molecules, exemplified by the C=C mode of Alexa 635. Moreover, single-wavelength SRS imaging of the Drosophila brain was presented. We envision that utilizing an MPC light source will substantially enhance the sensitivity and specificity of SRS by implementing EPR mode and spectral multiplexing.
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